There is strong national consensus about the pressing need to improve the delivery of end of life (EOL) care in the ICU. Despite decades of study and tests of interventions targeting specific elements, there continue to be concerns about prolonged use of ineffective therapies, resulting in suffering of both patients and families, as wel as moral distress of clinicians. The situation of chronically critically ill patients (CCI), with te complex interface of acute-on-chronic conditions and uncertain prognoses, presents particular challenges to clinicians and family surrogates in attempting to assess treatment effectiveness and identify the appropriate criteria and time for transitioning to a focus on palliation and EOL measures. While there is a growing body of work examining factors that influence decision making, the challenges faced by families and clinicians caring for CCI patients have been somewhat resistant to major improvements. Pre-existing clinician and family characteristics and philosophies (religious, cultural, personal), actual clinical trajectory of patient condition, expectations of likely outcomes, and evaluation of the effectiveness of treatment have all been shown to be relevant to decision making patterns. However, major intervention trials have failed to demonstrate significant gains. Previous studies have focused on a limited number of components or participants, using hypothetical scenarios or retrospective reports. In contrast, we will follow the natural trajectory of illness and decision making, which will allow us to examine the decision making system and factors influencing transitions or the lack of transitions from cure-oriented therapies to palliative and EOL interventions in the CCI. The proposed investigation will shift the current research paradigm in being the first to apply the principles o complexity science in examining how factors that influence transitions in actual practice interact. This will allow us to detect changes over time, and to account for relationships among various elements, such as religious beliefs of family surrogates, patient characteristics, and salient clue used by clinicians to trigger changes in goals. This will yield both a more accurate understanding of the phenomenon of transitions in the care of CCI, as well as new targets for intervention and guidance for tailored approaches. The primary aims are: (1) Examine the extent to which transitions to EOL care are predicted indirectly by characteristics (patient, clinician, family) and clinical triggers, and directly by outcome expectations (MD, family) and evaluation of treatment effectiveness; (2) Examine the extent to which evaluation of treatment effectiveness is predicted by characteristics (patient, clinician), outcome expectations (MD, family), and clinical triggers; (3) Examine the extent to which physician outcome expectations (survival, functional status, health related quality of life [HRQOL]) are predicted by physician characteristics, patient characteristics, and clinical triggers; (4) Examine the extent to which family outcome expectations (survival, functional status, HRQOL) are predicted by physician outcome expectations, family characteristics, and patient characteristics.